Such wastes are generated in the refining of fats and vegetable oils, in fat rendering, in tall oil recovery and refining, etc. Typical sources of such wastes include alkali refining, saponification, acidulation, tank and tank wagon cleanings, and accidental spills.
Usually such wastes are collected by skimming off a waste water tank. Frequently more sophisticated methods are used to achieve an even greater recovery in separation, for example, recovery in the manner of the Joseph and Kiegher waste water treatment process, U.S. Pat. No. 4,001,114.
In the absence of concentration of the oil skimming, such skimming contains about 50 percent by weight water. Its value as a commodity is about two cents ($0.02) per pound or approximately thirty-two cents ($0.32) per gallon of oil content. However, the oil portion of the skimming has considerable fuel value; for example, coconut oil has a heat of combustion of about 16,236 BTU/lb. and other oils such as rapeseed oil reach as high as about 17,424 BTU/lb. This fuel value cannot be readily recovered because of the relatively large amount of water associated with the waste prevents it from being utilized directly as a fuel.
To take advantage of the fuel value of the lipoidal waste, it is preferably necessary to reduce its water content substantially so that the waste water will not prevent its satisfactory combustion. The processes known in the art for separating the water fraction from lipoidal waste are tedious, complicated, and often quite unsatisfactory.
Applicant has discovered a process which allows the recovery of the fuel value of a lipoidal waste which is merely separated by skimming or other economical means from the waste water of a lipid processing operation. The present process not only disposes of the lipid; it eliminates the need for further processing and recovers the fuel value of the lipid fraction of the waste. The fuel value of the lipid is slightly less than the fuel value of petroleum; however, it is substantially more than the value of the waste as a commodity for other uses.